Electric welding is one of the ways to create one-piece joints, where the heating and melting of the metal of the parts to be joined is carried out using an electric arc. To implement the process and create an inextricable connection between the metal elements, electric welding machines are used. You can also cut metal structures or separate parts from them.
Classification
The scope of the apparatus is determined by the value of the welding current:
- Up to 150 A - household electric welding machines.
- Up to 250 A - semi-professional.
- More than 250 A - professional.
For the home foreman, an electric welding machine is absolutely necessary, because there is always a need to create one-piece joints when you need to install a fence, repair a defrosted water pipe, weld hinges to a gate or gate, make a brazier and much more. Professional welders and finished products purchased at the store are expensive. It is advisable to purchase an electric welding machine and metal billets, the costs of which are sometimes comparable with the purchase of finished products. Even if they are larger, especially savings will be felt in the future, when all the necessary equipment is already in stock.
The simplest welding device is a powerful transformer that connects directly to the network. It has many shortcomings: large weight and dimensions, significant energy consumption, the complexity of mastering the welding process. But there are also advantages: unpretentiousness, exceptional reliability, simplicity and cheapness.
It is difficult for an inexperienced welder to get a high-quality metal seam using a transformer. For proper operation, it is necessary to develop special skills. Working on alternating current creates difficulties with maintaining a stable welding arc. It is difficult for an amateur to choose the appropriate mode of operation.
Characteristics of welding transformers
The transformer contains primary and secondary step-down windings. The first is connected to the network, and the second is used for welding. The voltage on it is 30-60 V. Welding 220 volts is suitable for domestic use, and for industrial models with three-phase power supply of 380 V are often used. Connection is made through a machine through a separate line.
The choice of the unit is made according to the following characteristics.
- The limits of regulation of the welding current. The ability to change power means that you can select convenient modes of operation and change the diameter of the electrodes. The higher the maximum current, the larger the electrode size can be used.
- The diameter of the electrode. For household use, 3 mm is enough, and to increase the productivity of the welding process in the workshop or workshop, it should be 4-8 mm (current from 120 to 400 A). If the current strength is lower than required, the quality of the seam will be poor.
- Mains voltage. For domestic use, 220 V transformers are selected. Industrial models can operate from a three-phase network. Devices that can be connected for both types of power are available.
- Welding current. Which electrodes can be used, as well as the possibility of cutting metal, depends on its maximum value. The parameter is always indicated on the marking. For domestic use, transformer models with a rated current of 160-200 A are selected.
- Rated operational voltage. From the magnitude of the voltage at the output winding depends on how thick the metal can be welded.
- The operating mode or the duration of switching on indicates how much time the transformer is in welding mode. Powerful units can be switched on during the whole shift (100%), and for domestic use 40% is enough. If you go beyond the set limits, the device overheats and may be damaged.
- Transformer efficiency means the ratio between welding power output and power consumption. The maximum efficiency is about 80%. If it is lower, you should look for another model.
- Open circuit voltage facilitates the appearance of an electric arc as it increases. The safety threshold for the operator is 80 V at alternating current and 100 V at constant.
Welding rectifiers
Devices allow you to create a stable electric arc during operation. In addition to the transformer, the welding rectifier contains silicon or selenium blocks at the output, providing direct current to the welding rods.
It is much easier for a beginner to learn DC welding. In addition, cast iron, heat-resistant alloys and non-ferrous metals can be welded.
Electric welding machines have disadvantages: high cost, sensitivity to short circuit and power surges, as well as loss of power during operation. Despite this, the devices are used by both amateurs and professionals.
The welding rectifier is unpretentious in maintenance, but requires the following measures:
- checking the serviceability and reliability of the connection of contacts;
- Prevent moisture from entering inside and out;
- purge with compressed air to remove dust.
Which rectifier to choose?
How much an electric welding machine costs depends on power, maximum current and dimensions. For lovers, the Telwin Quality 220 AC / DC is suitable. Power is 6 kW, maximum current - 160 A, weight - 30 kg, price - up to 13 thousand rubles. Professional units for domestic use are usually not used due to the high price (100 thousand rubles and above), heavy weight, dimensions and power.
Welding inverters
The device is a current source, providing easy arc formation and automatic maintenance of its burning. Electric welding inverter apparatus operates as follows:
- 220 V voltage is supplied to the rectifier, where the signal is filtered and converted into direct current;
- high-frequency current is generated (inverter);
- the voltage drops to the welding level (transformer);
- AC is rectified.
The complexity of the circuit is associated with the need to reduce the size and weight of the transformer due to a significant increase in frequency. The output characteristics of the device are supported by an electronic controller. This is the main advantage of the apparatus, which can be used by a novice in the mode of a novice welder. If the welding transformer creates significant voltage surges in the network, the inverter does not overload it, and the ignition of the arc is softer.
The reliability of the device is lower than that of a transformer, due to the presence of an electronic circuit. It is sensitive to low air temperature and high humidity. The device generates electromagnetic interference, which is reduced in more expensive models.
Features of welding with an inverter
Devices have three functions.
- Hot start. In the initial period, the current increases and the heating of the electrode is not required, as in a transformer. When starting, the arc becomes more powerful, and welding is successful.
- Anti-sticking - an increase in the operating current when grasping the electrode. As a result, a quick separation occurs, and the welding parameters are instantly restored.
- Forcing the arc. The welding current parameters in anti-stick mode are adjusted so that the metal is not too sprayed.
Electric welding machine for home and garden
For everyday life, an inexpensive inverter with an optimal turn-on time of 60% is selected. It is often used by professionals, since with a leisurely work and with a small working current, the device can be turned on continuously. It is important that the mains voltage is normal. In this case, a device with a power of up to 160 A is selected. Welding of 220 volts, with a current of up to 200 A, is advisable when frequent surges in the mains voltage occur. From 180 A and above, it is possible to weld an electrode with a diameter of 4 mm sheets up to 5 mm thick.
Types of electric welding machines and manufacturers
Everyone is trying to buy a cheaper device, but with good features. Of the imported models, it is good to weld with Resanta and Interskol, in which the price category is from 6 to 11 thousand rubles. From domestic ones, “Torus” and “Cedar” have proven themselves well (price - 8-16 thousand rubles). Devices are cheaper than 6 thousand rubles. have lower quality.
Prices for electric welders do not always reflect the quality of the model. Decent devices are also selected by indirect indicators: the availability of service, high-quality instructions, positive reviews, etc.
Welding by Resantoy SAI 220 allows you to create reliable connections of products from tin and thick metal, thanks to a wide range of current control. For the device, it does not create problems to reduce the network voltage by 30% of the nominal.
Electric welding inverter apparatus "Caliber SVI-205AP" - a cheap model of Chinese manufacture is well suited for periodic use in everyday life. Judging by the reviews, the device does not always come across reliable, although there are often models that work without breakdowns for a long time.
Conclusion
Electric welding machines are selected according to needs. For the home master, a household model is suitable, and for a professional, you should choose a device more expensive, with the possibility of constant work during the shift. For any device, the correct welding technology and maintenance according to the instructions are required.